 
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .frame {
            display: inline-block;
            padding: 7px;
            background: linear-gradient(#00ffd4, #00ffd4) left top, linear-gradient(#00ffd4, #00ffd4) left top, linear-gradient(#00ffd4, #00ffd4) right top, linear-gradient(#00ffd4, #00ffd4) right top, linear-gradient(#00ffd4, #00ffd4) left bottom, linear-gradient(#00ffd4, #00ffd4) left bottom, linear-gradient(#00ffd4, #00ffd4) right bottom, linear-gradient(#00ffd4, #00ffd4) right bottom;
            background-repeat: no-repeat;
            background-size: 2px 20px, 20px 2px;
            width: 200px;
            height: 200px;
        }
        
        .frame-box {
            /* width: 100%;
            height: 100%;
            border: #00ffd4 1px solid;
            background: rgba(0, 0, 0, 0.3); */
        }
    </style>
</head>
 
<body>
    <div class="frame">
        <div class="frame-box">
        </div>
    </div>
    <div class="frame">
        <div class="frame-box">
        </div>
    </div>
</body>
 
</html>